simulation of energy recovery from chimney hot gases using an encapsulated phase change materials heat exchanger

The present study concentrated on devising a novel heat exchanger that employs materials that undergo phase transitions between solid and liquid states. in this context, air and water were selected as the fluids, while paraffin, potassium fluoride tetrahydrate, and potassium nitrate70%(kno3-lino3) were used as the phase change materials. the research scrutinized twelve distinct models in axisymmetric two-dimensional and transient modes. additionally, the proposed model was employed to assess the impact of factors such as the porosity, diameter, and type of encapsulated phase change material, as well as the temperature and flow rate of the inlet fluid on the thermal performance of the model. the results indicate that the simulated heat exchanger possesses the potential to harness energy from hot exhaust gases. the investigation of the particle diameter and porosity revealed that decreasing the porosity and increasing the particle diameter enhanced the energy storage and overall performance of the heat exchanger. furthermore, the examination of varying input temperature and flow rate demonstrated that raising the temperature of the chimney gases enhances the heat exchanger performance, while increasing the inlet fluid flow rate reduces the charging time. notably, the study also found that using potassium nitrate70% increase the amount of stored energy compared to other mentioned materials, due to the improved properties and high melting temperature.